Revision: 17923
Author: [email protected]
Date: Wed Nov 20 13:28:19 2013 UTC
Log: ARM: Optimize AccessArgumentsAt
Optimize register constraints and code generated for AccessArgumentsAt
Lithium instruction.
TEST=none
BUG=
[email protected]
Review URL: https://codereview.chromium.org/78093004
http://code.google.com/p/v8/source/detail?r=17923
Modified:
/branches/bleeding_edge/src/arm/lithium-arm.cc
/branches/bleeding_edge/src/arm/lithium-codegen-arm.cc
=======================================
--- /branches/bleeding_edge/src/arm/lithium-arm.cc Wed Nov 20 12:43:33 2013
UTC
+++ /branches/bleeding_edge/src/arm/lithium-arm.cc Wed Nov 20 13:28:19 2013
UTC
@@ -2550,15 +2550,8 @@
LInstruction* LChunkBuilder::DoAccessArgumentsAt(HAccessArgumentsAt*
instr) {
info()->MarkAsRequiresFrame();
LOperand* args = UseRegister(instr->arguments());
- LOperand* length;
- LOperand* index;
- if (instr->length()->IsConstant() && instr->index()->IsConstant()) {
- length = UseRegisterOrConstant(instr->length());
- index = UseOrConstant(instr->index());
- } else {
- length = UseTempRegister(instr->length());
- index = UseRegisterAtStart(instr->index());
- }
+ LOperand* length = UseRegisterOrConstantAtStart(instr->length());
+ LOperand* index = UseRegisterOrConstantAtStart(instr->index());
return DefineAsRegister(new(zone()) LAccessArgumentsAt(args, length,
index));
}
=======================================
--- /branches/bleeding_edge/src/arm/lithium-codegen-arm.cc Wed Nov 20
12:43:33 2013 UTC
+++ /branches/bleeding_edge/src/arm/lithium-codegen-arm.cc Wed Nov 20
13:28:19 2013 UTC
@@ -3186,20 +3186,35 @@
void LCodeGen::DoAccessArgumentsAt(LAccessArgumentsAt* instr) {
Register arguments = ToRegister(instr->arguments());
Register result = ToRegister(instr->result());
- if (instr->length()->IsConstantOperand() &&
- instr->index()->IsConstantOperand()) {
- int const_index = ToInteger32(LConstantOperand::cast(instr->index()));
+ // There are two words between the frame pointer and the last argument.
+ // Subtracting from length accounts for one of them add one more.
+ if (instr->length()->IsConstantOperand()) {
int const_length =
ToInteger32(LConstantOperand::cast(instr->length()));
- int index = (const_length - const_index) + 1;
- __ ldr(result, MemOperand(arguments, index * kPointerSize));
- } else {
+ if (instr->index()->IsConstantOperand()) {
+ int const_index =
ToInteger32(LConstantOperand::cast(instr->index()));
+ int index = (const_length - const_index) + 1;
+ __ ldr(result, MemOperand(arguments, index * kPointerSize));
+ } else {
+ Register index = ToRegister(instr->index());
+ __ rsb(result, index, Operand(const_length + 1));
+ __ ldr(result, MemOperand(arguments, result, LSL, kPointerSizeLog2));
+ }
+ } else if (instr->index()->IsConstantOperand()) {
+ Register length = ToRegister(instr->length());
+ int const_index =
ToInteger32(LConstantOperand::cast(instr->index()));
+ int loc = const_index - 1;
+ if (loc != 0) {
+ __ sub(result, length, Operand(loc));
+ __ ldr(result, MemOperand(arguments, result, LSL,
kPointerSizeLog2));
+ } else {
+ __ ldr(result, MemOperand(arguments, length, LSL,
kPointerSizeLog2));
+ }
+ } else {
Register length = ToRegister(instr->length());
Register index = ToRegister(instr->index());
- // There are two words between the frame pointer and the last argument.
- // Subtracting from length accounts for one of them add one more.
- __ sub(length, length, index);
- __ add(length, length, Operand(1));
- __ ldr(result, MemOperand(arguments, length, LSL, kPointerSizeLog2));
+ __ sub(result, length, index);
+ __ add(result, result, Operand(1));
+ __ ldr(result, MemOperand(arguments, result, LSL, kPointerSizeLog2));
}
}
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